AT&T is the major one that I know of that is still enforcing this policy. But they said they can unblock port 25 upon request. I am not sure how easyit is.It's trivial. A web form. You get the link when you try to send mail to port 25 anywhere else. At least with Yahoo/SBC dsl.I got the business class DSL from AT&T and no such nonsense exists.
Same here with U-Verse and a /29 of static IP's. No blocking since Day 1.